The present invention relates to the field of molds for molding and vulcanizing a tire tread. More specifically, the invention relates to the molds used for molding in the tread grooves which are partially or completely covered by an additional cover layer.
Document U.S. Pat. No. 4,057,089 discloses a pneumatic tire comprising a tread band. The tread band has a plurality of blocks. Each block extends in a curved manner to one side of the tread band towards the center of this tread band. More particularly, the blocks are curved along structural curvature of a parabola of the second order.
Document WO2012087826 discloses a molding element of a mold for molding and vulcanizing a tire tread. The molding element comprises a molding surface intended to mold part of the tire tread surface and a rib intended to mold a groove in the tread. In addition, the molding element comprises two lamellas positioned on either side of the rib at a certain distance from this rib, each lamella comprising a cutting edge, this cutting edge making an acute angle. The cutting means are able to cut a cover layer that covers a green tire. The rib itself will mold a groove in the tread and at the same time guide part of the cover layer into the groove thus molded.
It is an object of the present invention to propose a mold for molding curved blocks with cover layer.
A “tire” means all types of elastic tire whether or not subjected to an internal pressure.
A “green tire” or “green form” of a tire means a superposition of a plurality of semi-finished rubber products present in the form of strips or sheets, with or without reinforcement. The green tire is intended to be vulcanized in a mold in order to obtain the tire.
The “tread” of a tire means a quantity of rubber material bounded by lateral surfaces and by two main surfaces one of which is intended to come into contact with a road surface when the tire is running.
A “tread surface” means the surface formed by those points on the tire tread that come into contact with the road surface when the tire is running.
A “mold” means a collection of separate molding elements which, when brought closer towards one another, delimit a toroidal molding space.
A “molding element” of a mold means part of a mold. A molding element is, for example, a mold segment.
A “molding surface” of a molding element means the surface of the mold that is intended to mold the surface of the tire tread.
A “rib” of a molding element means a protrusion projecting from the molding surface. The width of the rib is 2 mm or more.
A “lamella” of a molding element means a protrusion projecting from the molding surface. The width of the lamella is less than 2 mm.
A “rib with a rounded end” means that the end of the rib is domed.
An “acute angle” means an angle smaller than 90°.